Presentation Information
[P03-408]The role of the nitrate-responsive two-component system SCO1369–SCO1370 in Streptomyces coelicolor A3(2)
○Chihaya Ito1, Masaki Takei1, Akito Hosoi2, Shinsaku Ito1, Shunsuke Yajima1, Yasuyuki Sasaki1 (1. Tokyo Universityb of Agriculture Faculty of Life Sciences (Japan), 2. NODAI Genome Reserch Center Tokyo Universityb of Agriculture (Japan))
Keywords:
streptomyces coelicolor,two-component system,nitrate,signal transduction
[Purpose]
In Streptomyces coelicolor A3(2), a nitrogen metabolic cycle in which nitrate, nitrite, and nitric oxide (NO) circulate has been reported. NO generated through this cycle is utilized as a signaling molecule; however, the signal transduction mechanisms of other nitrogen oxides remain poorly understood.In addition, the expression of sco1369 and sco1370 is markedly upregulated in an NO-deficient strain lacking nitrate reductase Nar (Δnar). In this study, we aimed to elucidate the molecular mechanisms of the signaling system associated with the nitrogen oxide metabolic cycle in Streptomyces coelicolor A3(2) through functional analysis of the two-component system composed of sco1369 and sco1370.
[Method]
Gene disruption mutants (Δsco1370, Δnar, and ΔnarΔsco1370) were constructed, and antibiotic production and morphological differentiation were evaluated. Gene expression of nitrate-responsive genes was analyzed by qRT-PCR. In addition, to identify the input signal of this two-component system, nitrate and nitrite were added, and the resulting responses were evaluated.
[Results]
The Δsco1370 strain exhibited little morphological changes compared to the wild type (WT). In contrast, the ΔnarΔsco1370 strain showed differences in sporulation compared to the Δnar strain, along with increased production of the blue-pigmented antibiotic actinorhodin (ACT). In the ΔnarΔsco1370 strain, the expression levels of sco1368 and sco1369 were decreased, whereas those of the ACT biosynthesis regulatory gene actII-orf4 and the sporulation-related gene ssgB were increased. Furthermore, expressions of sco1369 and sco1370 were induced by nitrate but not by nitrite. Notably, nitrate-induced increases in antibiotic production and colony size were not observed in the Δsco1370 strain.
[Consideration]
These results suggest that the SCO1369–SCO1370 two-component system functions as a nitrate-responsive signaling system. In particular, the loss of nitrate-responsive morphological changes in the Δsco1370 strain indicates that this system is involved in nitrate signal perception and/or downstream regulation. Moreover, disruption of sco1370 in the Δnar background enhanced antibiotic production and altered sporulation, while decreasing the expression of sco1368 and sco1369, suggesting that this system modulates antibiotic production and morphological differentiation in response to nitrate derived from the nitrogen metabolic cycle.
[Conclusion]
The SCO1369–SCO1370 system likely functions as a nitrate-responsive two-component system and is involved in the regulation of antibiotic production and morphological differentiation associated with nitrate derived from the nitrogen metabolic cycle.
In Streptomyces coelicolor A3(2), a nitrogen metabolic cycle in which nitrate, nitrite, and nitric oxide (NO) circulate has been reported. NO generated through this cycle is utilized as a signaling molecule; however, the signal transduction mechanisms of other nitrogen oxides remain poorly understood.In addition, the expression of sco1369 and sco1370 is markedly upregulated in an NO-deficient strain lacking nitrate reductase Nar (Δnar). In this study, we aimed to elucidate the molecular mechanisms of the signaling system associated with the nitrogen oxide metabolic cycle in Streptomyces coelicolor A3(2) through functional analysis of the two-component system composed of sco1369 and sco1370.
[Method]
Gene disruption mutants (Δsco1370, Δnar, and ΔnarΔsco1370) were constructed, and antibiotic production and morphological differentiation were evaluated. Gene expression of nitrate-responsive genes was analyzed by qRT-PCR. In addition, to identify the input signal of this two-component system, nitrate and nitrite were added, and the resulting responses were evaluated.
[Results]
The Δsco1370 strain exhibited little morphological changes compared to the wild type (WT). In contrast, the ΔnarΔsco1370 strain showed differences in sporulation compared to the Δnar strain, along with increased production of the blue-pigmented antibiotic actinorhodin (ACT). In the ΔnarΔsco1370 strain, the expression levels of sco1368 and sco1369 were decreased, whereas those of the ACT biosynthesis regulatory gene actII-orf4 and the sporulation-related gene ssgB were increased. Furthermore, expressions of sco1369 and sco1370 were induced by nitrate but not by nitrite. Notably, nitrate-induced increases in antibiotic production and colony size were not observed in the Δsco1370 strain.
[Consideration]
These results suggest that the SCO1369–SCO1370 two-component system functions as a nitrate-responsive signaling system. In particular, the loss of nitrate-responsive morphological changes in the Δsco1370 strain indicates that this system is involved in nitrate signal perception and/or downstream regulation. Moreover, disruption of sco1370 in the Δnar background enhanced antibiotic production and altered sporulation, while decreasing the expression of sco1368 and sco1369, suggesting that this system modulates antibiotic production and morphological differentiation in response to nitrate derived from the nitrogen metabolic cycle.
[Conclusion]
The SCO1369–SCO1370 system likely functions as a nitrate-responsive two-component system and is involved in the regulation of antibiotic production and morphological differentiation associated with nitrate derived from the nitrogen metabolic cycle.
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